<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button onclick="change()">change</button>
    <div>hello</div>
</body>
    <script>
        function change(){
            const div = document.querySelector('div');
            let n = document.createElement('button');
            n.textContent = 'button1';
            div.appendChild(n);

            n = document.createTextNode('       ');
            div.appendChild(n);

            n = document.createElement('button');
            n.textContent = 'button2';
            div.appendChild(n);
        }
    </script>
</html>